Laminated magnetic inductor stack with high frequency peak quality factor

ABSTRACT

Embodiments are directed to a method of forming a magnetic stack arrangement of a laminated magnetic inductor having a high frequency peak quality factor (Q). A first magnetic stack is formed having one or more magnetic layers alternating with one or more insulating layers in a first inner region of a laminated magnetic inductor. A second magnetic stack is formed opposite a surface of the first magnetic stack in an outer region of the laminated magnetic inductor. A third magnetic stack is formed opposite a surface of the second magnetic stack in a second inner region of the laminated magnetic inductor. The insulating layers are formed such that a thickness of an insulating layer in the second magnetic stack is greater than a thickness of an insulating layer in the first magnetic stack.

BACKGROUND

The present invention generally relates to fabrication methods andresulting structures for on-chip magnetic devices. More specifically,the present invention relates to on-chip magnetic structures, e.g., alaminated magnetic inductor stack, having a high frequency peak qualityfactor.

Inductors, resistors, and capacitors are the main passive elementsconstituting an electronic circuit. Inductors are used in circuits for avariety of purposes, such as in noise reduction, inductor-capacitor (LC)resonance calculators, and power supply circuitry. Inductors can beclassified as one of various types, such as a winding-type inductor or alaminated film-type inductor. Winding-type inductors are manufactured bywinding a coil around, or printing a coil on, a ferrite core. Laminatedfilm-type inductors are manufactured by stacking alternating magnetic ordielectric materials to form laminated stacks.

Among the various types of inductors the laminated film-type inductor iswidely used in power supply circuits requiring miniaturization and highcurrent due to the reduced size and improved inductance per coil turn ofthese inductors relative to other inductor types. A known laminatedinductor configuration includes one or more magnetic or dielectriclayers laminated with conductive patterns. The conductive patterns aresequentially connected by a conductive via formed in each of the layersand overlapped in a laminated direction to form a spiral-structuredcoil. Typically, both ends of the coil are drawn out to an outer surfaceof a laminated body for connection to external terminals.

SUMMARY

Embodiments of the present invention are directed to a method forfabricating a magnetic stack arrangement of a laminated magneticinductor. A non-limiting example of the method includes forming a firstmagnetic stack having one or more magnetic layers alternating with oneor more insulating layers in a first region of a laminated magneticinductor. A second magnetic stack is formed having one or more magneticlayers alternating with one or more insulating layers opposite a surfaceof the first magnetic stack in an outer region of the laminated magneticinductor. A third magnetic stack is formed having one or more magneticlayers alternating with one or more insulating layers opposite a surfaceof the second magnetic stack in a second inner region of the laminatedmagnetic inductor. The insulating layers are formed such that athickness of an insulating layer in the second magnetic stack is greaterthan a thickness of an insulating layer in the first magnetic stack.

Embodiments of the present invention are directed to a method forfabricating a magnetic stack arrangement of a laminated magneticinductor. A non-limiting example of the method includes forming a firstinsulating layer proximate to a conductive coil of the laminatedmagnetic inductor. A second insulating layer is formed proximate to theconductive coil opposite a surface of the first insulating layer. Athird insulating layer is formed between the first and second insulatinglayers such that the third insulating layer is further from theconductive coil than either the first insulating layer or the secondinsulating layer. The insulating layers are formed such that a thicknessof the third insulating layer is greater than a thickness of either thefirst or second insulating layers.

Embodiments of the present invention are directed to a laminatedmagnetic inductor. A non-limiting example of the laminated magneticinductor includes a first inner region having one or more magneticlayers alternating with one or more insulating layers. An outer regionhaving one or more magnetic layers alternating with one or moreinsulating layers is formed opposite a surface of the first innerregion. A second inner region having one or more magnetic layersalternating with one or more insulating layers is formed opposite asurface of the outer region. The insulating layers are formed such thata thickness of an insulating layer in the outer region is greater than athickness of an insulating layer in either the first or second innerregions.

Additional technical features and benefits are realized through thetechniques of the present invention. Embodiments and aspects of theinvention are described in detail herein and are considered a part ofthe claimed subject matter. For a better understanding, refer to thedetailed description and to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The specifics of the exclusive rights described herein are particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification.

The foregoing and other features and advantages of the embodiments ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 depicts a laminated magnetic inductor after a fabricationoperation according to embodiments of the invention;

FIG. 2 depicts a laminated magnetic inductor after a fabricationoperation according to embodiments of the invention;

FIG. 3 depicts a laminated magnetic inductor after a fabricationoperation according to embodiments of the invention;

FIG. 4 depicts a laminated magnetic inductor after a fabricationoperation according to embodiments of the invention;

FIG. 5 depicts a laminated magnetic inductor after a fabricationoperation according to embodiments of the invention;

FIG. 6 depicts a laminated magnetic inductor after a fabricationoperation according to embodiments of the invention; and

FIG. 7 depicts a flow diagram illustrating a method according to one ormore embodiments of the invention.

The diagrams depicted herein are illustrative. There can be manyvariations to the diagram or the operations described therein withoutdeparting from the spirit of the invention. For instance, the actionscan be performed in a differing order or actions can be added, deletedor modified.

In the accompanying figures and following detailed description of thedisclosed embodiments, the various elements illustrated in the figuresare provided with two or three digit reference numbers. With minorexceptions, the leftmost digit(s) of each reference number correspond tothe figure in which its element is first illustrated.

DETAILED DESCRIPTION

For the sake of brevity, conventional techniques related tosemiconductor device and integrated circuit (IC) fabrication may or maynot be described in detail herein. Moreover, the various tasks andprocess steps described herein can be incorporated into a morecomprehensive procedure or process having additional steps orfunctionality not described in detail herein. In particular, varioussteps in the manufacture of laminated inductor devices are well knownand so, in the interest of brevity, many conventional steps will only bementioned briefly herein or will be omitted entirely without providingthe well-known process details.

Turning now to an overview of technologies that are more specificallyrelevant to aspects of the invention, as previously noted herein,laminated film-type inductors offer reduced size and improved inductanceper coil turn relative to other inductor types. For this reason,laminated film-type inductors are widely used in applications requiringminiaturization and high current, such as power supply circuitry. Theintegration of inductive power converters onto silicon is one path toreducing the cost, weight, and size of electronic devices.

Laminated film-type inductor performance can be improved by addinglayers of magnetic film. There are two basic laminated film-typemagnetic inductor configurations: the closed yoke type laminatedinductor and the solenoid type laminated inductor. The closed yoke typelaminated inductor includes a metal core (typically a copper wire) andmagnetic material wrapped around the core. Conversely, the solenoid typelaminated inductor includes a magnetic material core and a conductivewire (e.g., copper wire) wrapped around the magnetic material. Both theclosed yoke type laminated inductor and the solenoid type laminatedinductor benefit by having very thick magnetic stacks or yokes (e.g.,magnetic layers having a thickness of greater than about 50 nm). Thickmagnetic layers offer faster throughput and are significantly moreefficient to deposit. There are challenges, however, in providinglaminated film-type inductor architectures having thick magnetic layers.

One such challenge is addressing the increased loss in energy due to thepowerful eddy currents associated with inductors having multipledielectric layer thicknesses. Eddy currents (also known as Foucaultcurrents) are loops of electrical current induced by a changing magneticfield in a conductor. Eddy currents flow in closed loops withinconductors in a plane perpendicular to the magnetic field. Eddy currentsare created when the time varying magnetic fields in the magnetic layerscreate an electric field that drives a circular current flow. Theselosses can be substantial and increase with the thickness of themagnetic layers.

The magnetic loss caused by eddy currents in a thick film inductor islargest in the region of the inductor where the coil is in closeproximity to the magnetic material. Specifically, magnetic layers closerto the coil (that is, the “inner layers”) have larger losses thanmagnetic layers further from the coil (the “outer layers”). Moreover,magnetic flux densities in the space occupied by inner layers aregenerally higher than those characterizing the outer layers due to themagnetic reluctance of the insulating layers (also called spacer layers)interposed between the winding and the outer layers. Due to theserelatively large magnetic flux densities in the space occupied by theinner layers, the inner layers tend to magnetically saturate at lowerdrive currents and have greater losses than the outer layers.Accordingly, the inner layer region is a critical region—the losses inthis critical region dominate the overall losses of the inductor.

As magnetic film thicknesses increase, the eddy currents become severeenough to degrade the quality factor (also known as “Q”) of theinductor. The quality factor of an inductor is the ratio of itsinductive reactance to its resistance at a given frequency, and is ameasure of its efficiency. The maximum attainable quality factor for agiven inductor across all frequencies is known as peak Q (or maximum Q).Some applications can require the peak Q to be at a low frequency andother applications can require the peak Q to be at a high frequency.

Turning now to an overview of the aspects of the invention, one or moreembodiments of the invention address the above-described shortcomings byproviding methods of fabricating a laminated magnetic inductor having ahigh frequency peak Q. The frequency at which peak Q occurs for a giveninductor is, in general, inversely proportional to permeability.Permeability (μ) is the degree of magnetization that a material obtainsin response to an applied magnetic field. Incorporating materials withhigh permeability in an inductor increases losses and shifts thefrequency of peak Q to a higher frequency.

By patterning specific regions of the inductor into laminations havingthin or thick dielectric layers the frequency of peak Q can be adjusted.In particular, inner regions of the inductor (i.e., those criticalregions proximate to the conductive coil) are patterned with laminationshaving thin dielectric layers to increase the effective permeability ofthe inner layers and to shift the frequency of peak Q to a higherfrequency. In this manner, eddy current losses in the critical regionsof the inductor are leveraged to modulate the frequency of peak Q. Theouter regions of the inductor (i.e., those regions positioned fartheraway from the conductive coil than the inner regions) are patterned withlaminations having thick dielectric layers. Patterning the outer layerswith thick dielectric layers decreases the effective permeability ofthese layers and reduces losses.

Turning now to a more detailed description of aspects of the presentinvention, FIG. 1 depicts a cross-sectional view of a structure 100along a direction X-X′ having a dielectric layer 102 (also referred toas a bottom dielectric layer) formed opposite a surface of a substrate104 during an intermediate operation of a method of fabricating asemiconductor device according to embodiments of the invention. Thedielectric layer 102 can be any suitable material, such as, for example,a low-k dielectric, silicon nitride (SiN), silicon dioxide (SiO₂),silicon oxynitride (SiON), and silicon oxycarbonitride (SiOCN). Anyknown manner of forming the dielectric layer 102 can be utilized. Insome embodiments, the dielectric layer 102 is SiO₂ conformally formed onexposed surfaces of the substrate 104 using a conformal depositionprocess such as PVD, CVD, plasma-enhanced CVD (PECVD), or a combinationthereof. In some embodiments, the dielectric layer 102 is conformallyformed to a thickness of about 50 nm to about 400 nm, although otherthicknesses are within the contemplated scope of embodiments of theinvention.

The substrate 104 can be a wafer and can have undergone knownsemiconductor front end of line processing (FEOL), middle of the lineprocessing (MOL), and back end of the line processing (BEOL). FEOLprocesses can include, for example, wafer preparation, isolation, wellformation, gate patterning, spacer, extension and source/drainimplantation, and silicide formation. The MOL can include, for example,gate contact formation, which can be an increasingly challenging part ofthe whole fabrication flow, particularly for lithography patterning. Inthe BEOL, interconnects can be fabricated with, for example, a dualdamascene process using PECVD deposited interlayer dielectric (ILDs),PVD metal barriers, and electrochemically plated conductive wirematerials. The substrate 104 can include a bulk silicon substrate or asilicon on insulator (SOI) wafer. The substrate 104 can be made of anysuitable material, such as, for example, Ge, SiGe, GaAs, InP, AlGaAs, orInGaAs.

A conductive coil 106 is formed in the dielectric layer 102 and adielectric layer 600 (depicted in FIG. 6) and helically around portionsof the structure 100. The conductive coil 106 can be formed by, forexample, depositing copper lines in the dielectric layer 102, formingvias on top of the copper lines, and then depositing coper lines on topof the vias in the dielectric layer 600. For ease of discussionreference is made to operations performed on and to a conductive coil106 having six turns or windings formed in the dielectric layer 102(e.g., the conductive coil 106 wraps through the dielectric layer 102 atotal of six times). It is understood, however, that the dielectriclayer 102 can include any number of windings. For example, thedielectric layer 102 can include a single winding, 2 windings, 5windings, 10 windings, or 20 windings, although other winding counts arewithin the contemplated scope of embodiments of the invention. Theconductive coil 106 can be made of any suitable conducting material,such as, for example, metal (e.g., tungsten, titanium, tantalum,ruthenium, zirconium, cobalt, copper, aluminum, lead, platinum, tin,silver, gold), conducting metallic compound material (e.g., tantalumnitride, titanium nitride, tantalum carbide, titanium carbide, titaniumaluminum carbide, tungsten silicide, tungsten nitride, ruthenium oxide,cobalt silicide, nickel silicide), carbon nanotube, conductive carbon,graphene, or any suitable combination of these materials.

FIG. 2 depicts a cross-sectional view of the structure 100 along thedirection X-X′ after forming a first inner layer region 200 opposite asurface of the dielectric layer 102 during an intermediate operation ofa method of fabricating a semiconductor device according to embodimentsof the invention. The first inner layer region 200 (also referred to asa magnetic stack) includes one or more inner magnetic layers (e.g.,inner magnetic layer 202) alternating with one or more insulating layers(e.g., insulating layer 204). The first inner layer region 200 is formedby depositing alternating magnetic and insulating layers. For ease ofdiscussion the first inner layer region 200 is depicted as having threeinner magnetic layers alternating with three insulating layers. It isunderstood, however, that the first inner layer region 200 can includeany number of inner magnetic layers alternating with a correspondingnumber of insulating layers. For example, the first inner layer region200 can include a single inner magnetic layer, two inner magneticlayers, five inner magnetic layers, eight inner magnetic layers, or anynumber of inner magnetic layers, along with a corresponding number ofinsulating layers (i.e., as appropriate to form an inner layer regionhaving a topmost insulating layer on a topmost inner magnetic layer andan insulating layer between each pair of adjacent inner magneticlayers).

The inner magnetic layer 202 can be made of any suitable magneticmaterial known in the art, such as, for example, a ferromagneticmaterial, soft magnetic material, iron alloy, nickel alloy, cobaltalloy, ferrites, plated materials such as permalloy, or any suitablecombination of these materials. In some embodiments, the inner magneticlayer 202 includes a Co containing magnetic material, FeTaN, FeNi,FeAlO, or combinations thereof. Any known manner of forming the innermagnetic layer 202 can be utilized. The inner magnetic layer 202 can bedeposited through vacuum deposition technologies (i.e., sputtering) orelectrodepositing through an aqueous solution. In some embodiments, theinner magnetic layer 202 is conformally formed on exposed surfaces ofthe dielectric layer 102 using a conformal deposition process such asPVD, CVD, PECVD, or a combination thereof. In some embodiments, theinner magnetic layer 202 is conformally formed to a thickness of about50 nm to about 500 nm, although other thicknesses are within thecontemplated scope of embodiments of the invention.

The insulating layer 204 serves to isolate the adjacent magneticmaterial layers from each other in the stack and can be made of anysuitable non-magnetic insulating material known in the art, such as, forexample, aluminum oxides (e.g., alumina), silicon oxides (e.g., SiO₂),silicon nitrides, silicon oxynitrides (SiO_(x)N_(y)), polymers,magnesium oxide (MgO), or any suitable combination of these materials.Any known manner of forming the insulating layer 204 can be utilized. Insome embodiments, the insulating layer 204 is conformally formed onexposed surfaces of the inner magnetic layer 202 using a conformaldeposition process such as PVD, CVD, PECVD, or a combination thereof.

As discussed previously herein, the target thickness of the insulatinglayers in the first inner layer region 200 (e.g., insulating layer 204)is adjusted to increase the effective permeability of the inner layersand to shift the frequency of peak Q to a higher frequency. Theinsulating layer 204 is conformally formed to a relatively thinthickness (i.e., a thickness of about 0.5 nm to about 20 nm, althoughother thicknesses are within the contemplated scope of embodiments ofthe invention) to increase losses and to shift the frequency of peak Qto a higher frequency. In some embodiments, the thickness of theinsulating layer 204 can be 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 10 nm,15 nm, and 20 nm.

FIG. 3 depicts a cross-sectional view of the structure 100 along thedirection X-X′ after forming an outer layer region 300 opposite asurface of the first inner layer region 200 during an intermediateoperation of a method of fabricating a semiconductor device according toembodiments of the invention. The outer layer region 300 includes one ormore outer magnetic layers (e.g., outer magnetic layer 302) alternatingwith one or more insulating layers (e.g., insulating layer 304). Theouter layer region 300 is formed in a similar manner as the first innerlayer region 200—by depositing alternating magnetic and insulatinglayers. For ease of discussion the outer layer region 300 is depicted ashaving three outer magnetic layers alternating with three insulatinglayers. It is understood, however, that the outer layer region 300 caninclude any number of outer magnetic layers alternating with acorresponding number of insulating layers. For example, the outer layerregion 300 can include a single outer magnetic layer, two outer magneticlayers, five outer magnetic layers, eight outer magnetic layers, or anynumber of outer magnetic layers, along with a corresponding number ofinsulating layers (i.e., as appropriate to form an outer layer regionhaving a topmost insulating layer on a topmost outer magnetic layer andan insulating layer between each pair of adjacent outer magneticlayers). It is further understood that the outer layer region 300 caninclude a different number of magnetic layers than the first inner layerregion 200.

The outer magnetic layer 302 can be made of any suitable magneticmaterial and can be formed using any suitable process in a similarmanner as the inner magnetic layer 202. In some embodiments, the outermagnetic layer 302 is conformally formed to a thickness of about 50 nmto about 500 nm, although other thicknesses are within the contemplatedscope of embodiments of the invention. The outer magnetic layer 302 canhave a same thickness, a larger thickness, or a smaller thickness as theinner magnetic layer 202 in the first inner layer region 200.

The insulating layer 304 can be made of any suitable non-magneticinsulating material and can be formed using any suitable process in asimilar manner as the insulating layer 204. As discussed previouslyherein, the insulating layer 304 in the outer layer region 300 is formedto a relatively large thickness (i.e., a thickness of at least 50 nm) todecrease the effective permeability of these layers and to reducelosses. In some embodiments, the insulating layer 204 is conformallyformed to a thickness of about 100 nm to about 1 μm. The thickness ofthe insulating layer 304 in the outer layer region 300 is greater thanthe thickness of the insulating layer 204 in the first inner layerregion 200. In some embodiments, the thickness of the insulating layer304 is two times, three times, four times, five times, ten times, twentytimes, or fifty times the thickness of the insulating layer 204,although other thicknesses are within the contemplated scope ofembodiments of the invention.

FIG. 4 depicts a cross-sectional view of the structure 100 along thedirection X-X′ after forming a second inner layer region 400 opposite asurface of the outer layer region 300 during an intermediate operationof a method of fabricating a semiconductor device according toembodiments of the invention. The second inner layer region 400 includesone or more outer magnetic layers (e.g., second inner magnetic layer402) alternating with one or more insulating layers (e.g., insulatinglayer 404). The second inner layer region 400 is formed in a similarmanner as the first inner layer region 200—by depositing alternatingmagnetic and insulating layers. For ease of discussion the second innerlayer region 400 is depicted as having three outer magnetic layersalternating with three insulating layers. It is understood, however,that the second inner layer region 400 can include any number of outermagnetic layers alternating with a corresponding number of insulatinglayers. For example, the second inner layer region 400 can include asingle outer magnetic layer, two outer magnetic layers, five outermagnetic layers, eight outer magnetic layers, or any number of outermagnetic layers, along with a corresponding number of insulating layers(i.e., as appropriate to form an inner layer region having a topmostinsulating layer on a topmost outer magnetic layer and an insulatinglayer between each pair of adjacent outer magnetic layers). It isfurther understood that the second inner layer region 400 can include adifferent number of magnetic layers than the first inner layer region200.

The second inner magnetic layer 402 can be made of any suitable magneticmaterial and can be formed using any suitable process in a similarmanner as the inner magnetic layer 202. In some embodiments, the secondinner magnetic layer 402 is conformally formed to a thickness of about50 nm to about 500 nm, although other thicknesses are within thecontemplated scope of embodiments of the invention. The second innermagnetic layer 402 can have a same thickness, a larger thickness, or asmaller thickness as the inner magnetic layer 202 in the first innerlayer region 200.

The insulating layer 404 can be made of any suitable non-magneticinsulating material and can be formed using any suitable process in asimilar manner as the insulating layer 204. As discussed previouslyherein, the target thickness of the insulating layers in the secondinner layer region 400 (e.g., insulating layer 404) is adjusted toincrease the effective permeability of the inner layers and to shift thefrequency of peak Q to a higher frequency. In some embodiments, theinsulating layer 404 is conformally formed to a relatively thinthickness (i.e., a thickness of about 0.5 nm to about 20 nm, althoughother thicknesses are within the contemplated scope of embodiments ofthe invention) to increase losses and to shift the frequency of peak Qto a higher frequency. The insulating layer 404 can have a samethickness, a larger thickness, or a smaller thickness as the insulatinglayer 204 in the first inner layer region 200.

FIG. 5 depicts a cross-sectional view of the structure 100 along thedirection X-X′ after patterning the first inner layer region 200, theouter layer region 300, and the second inner layer region 400 to formlaminated stacks 500, 502, and 504 during an intermediate operation of amethod of fabricating a semiconductor device according to embodiments ofthe invention. Any known method for patterning laminated stacks can beused, such as, for example, a wet etch, a dry etch, or a combination ofsequential wet and/or dry etches. In some embodiments, the laminatedstacks 500, 502, and 504 are formed by removing portions of the firstinner layer region 200, the outer layer region 300, and the second innerlayer region 400 selective to the dielectric layer 102. For ease ofdiscussion the structure 100 is depicted as having three laminatedstacks (e.g., the laminated stacks 500, 502, and 504). It is understood,however, that the structure 100 can include any number of laminatedstacks. For example, the structure 100 can include a single laminatedstack, two laminated stacks, five laminated stacks, eight laminatedstacks, or any number of laminated stacks.

FIG. 6 depicts a cross-sectional view of the structure 100 along thedirection X-X′ after forming a dielectric layer 600 opposite a surfaceof the dielectric layer 102 during an intermediate operation of a methodof fabricating a semiconductor device according to embodiments of theinvention. The dielectric layer 600 can be any suitable insulatingmaterial, such as, for example, a low-k dielectric, SiO₂, SiON, andSiOCN. Any known manner of forming the dielectric layer 600 can beutilized. In some embodiments, the dielectric layer 600 is SiO₂conformally formed opposite a surface of the dielectric layer 102 usinga conformal deposition process such as PVD, CVD, PECVD, or a combinationthereof. In some embodiments, the dielectric layer 600 is conformallyformed to a thickness sufficient to cover a surface of the laminatedstacks 500, 502, and 504. In some embodiments, a CMP selective to thelaminated stacks 500, 502, and 504 planarizes the dielectric layer 600to a surface of the laminated stacks 500, 502, and 504.

A dielectric layer 602 (also referred to as a top dielectric layer) isformed opposite a surface of the dielectric layer 600 during anintermediate operation of a method of fabricating a semiconductor deviceaccording to embodiments of the invention. The dielectric layer 602 canbe any suitable material, such as, for example, a low-k dielectric, SIN,SiO₂, SiON, and SiOCN. Any known manner of forming the dielectric layer602 can be utilized. In some embodiments, the dielectric layer 602 isSiO₂ conformally formed on exposed surfaces of the dielectric layer 600using a conformal deposition process such as PVD, CVD, PECVD, or acombination thereof. In some embodiments, the dielectric layer 602 isconformally formed to a thickness of about 50 nm to about 400 nm,although other thicknesses are within the contemplated scope ofembodiments of the invention.

As discussed previously herein, the conductive coil 106 is formed in thedielectric layer 602 and helically wraps around portions of thestructure 100. For ease of discussion reference is made to operationsperformed on and to a conductive coil 106 having six turns or windingsformed in the dielectric layer 602. It is understood, however, that thedielectric layer 602 can include any number of windings. For example,the dielectric layer 602 can include a single winding, 2 windings, 5windings, 10 windings, or 20 windings, although other winding counts arewithin the contemplated scope of embodiments of the invention.

FIG. 7 depicts a flow diagram illustrating a method for forming alaminated magnetic inductor according to one or more embodiments of theinvention. As shown at block 702, a first magnetic stack having one ormore magnetic layers alternating with one or more insulating layers isformed in a first inner region of a laminated magnetic inductor. Themagnetic layers of the first magnetic stack can be formed in a similarmanner as the inner magnetic layer 202 (as depicted in FIG. 2) accordingto one or more embodiments. The insulating layers of the first magneticstack can be formed in a similar manner as the insulating layer 204 (asdepicted in FIG. 2) according to one or more embodiments.

As shown at block 704, a second magnetic stack having one or moremagnetic layers alternating with one or more insulating layers is formedin an outer region of the laminated magnetic inductor opposite a surfaceof the first inner region. The magnetic layers of the second magneticstack can be formed in a similar manner as the outer magnetic layer 302(as depicted in FIG. 3) according to one or more embodiments. Theinsulating layers of the first magnetic stack can be formed in a similarmanner as the insulating layer 304 (as depicted in FIG. 3) according toone or more embodiments.

As shown at block 706, a third magnetic stack having one or moremagnetic layers alternating with one or more insulating layers is formedin a second inner region of the laminated magnetic inductor opposite asurface of the outer region. The magnetic layers of the third magneticstack can be formed in a similar manner as the second inner magneticlayer 402 (as depicted in FIG. 4) according to one or more embodiments.The insulating layers of the third magnetic stack can be formed in asimilar manner as the insulating layer 404 (as depicted in FIG. 4)according to one or more embodiments.

As discussed previously herein, the first, second, and third magneticstacks are structured such that a thickness of the insulating layers inthe outer layer region 300 is greater than a thickness of the insulatinglayers in the first inner layer region 200 or the second inner layerregion 400. In this manner, eddy current losses can be leveraged in thecritical regions (i.e., the first and second inner regions 200 and 400)to modulate the frequency of peak Q while still mitigating losses in thenoncritical regions (i.e., the outer region 300).

Various embodiments of the present invention are described herein withreference to the related drawings. Alternative embodiments can bedevised without departing from the scope of this invention. Althoughvarious connections and positional relationships (e.g., over, below,adjacent, etc.) are set forth between elements in the followingdescription and in the drawings, persons skilled in the art willrecognize that many of the positional relationships described herein areorientation-independent when the described functionality is maintainedeven though the orientation is changed. These connections and/orpositional relationships, unless specified otherwise, can be direct orindirect, and the present invention is not intended to be limiting inthis respect. Similarly, the term “coupled” and variations thereofdescribes having a communications path between two elements and does notimply a direct connection between the elements with no interveningelements/connections between them. All of these variations areconsidered a part of the specification. Accordingly, a coupling ofentities can refer to either a direct or an indirect coupling, and apositional relationship between entities can be a direct or indirectpositional relationship. As an example of an indirect positionalrelationship, references in the present description to forming layer “A”over layer “B” include situations in which one or more intermediatelayers (e.g., layer “C”) is between layer “A” and layer “B” as long asthe relevant characteristics and functionalities of layer “A” and layer“B” are not substantially changed by the intermediate layer(s).

The following definitions and abbreviations are to be used for theinterpretation of the claims and the specification. As used herein, theterms “comprises,” “comprising,” “includes,” “including,” “has,”“having,” “contains” or “containing,” or any other variation thereof,are intended to cover a non-exclusive inclusion. For example, acomposition, a mixture, process, method, article, or apparatus thatcomprises a list of elements is not necessarily limited to only thoseelements but can include other elements not expressly listed or inherentto such composition, mixture, process, method, article, or apparatus.

Additionally, the term “exemplary” is used herein to mean “serving as anexample, instance or illustration.” Any embodiment or design describedherein as “exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments or designs. The terms “at least one”and “one or more” are understood to include any integer number greaterthan or equal to one, i.e. one, two, three, four, etc. The terms “aplurality” are understood to include any integer number greater than orequal to two, i.e. two, three, four, five, etc. The term “connection”can include an indirect “connection” and a direct “connection.”

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” etc., indicate that the embodiment describedcan include a particular feature, structure, or characteristic, butevery embodiment may or may not include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

For purposes of the description hereinafter, the terms “upper,” “lower,”“right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” andderivatives thereof shall relate to the described structures andmethods, as oriented in the drawing figures. The terms “overlying,”“atop,” “on top,” “positioned on” or “positioned atop” mean that a firstelement, such as a first structure, is present on a second element, suchas a second structure, wherein intervening elements such as an interfacestructure can be present between the first element and the secondelement. The term “direct contact” means that a first element, such as afirst structure, and a second element, such as a second structure, areconnected without any intermediary conducting, insulating orsemiconductor layers at the interface of the two elements.

The terms “about,” “substantially,” “approximately,” and variationsthereof, are intended to include the degree of error associated withmeasurement of the particular quantity based upon the equipmentavailable at the time of filing the application. For example, “about”can include a range of ±8% or 5%, or 2% of a given value.

The phrase “selective to,” such as, for example, “a first elementselective to a second element,” means that the first element can beetched and the second element can act as an etch stop.

The term “conformal” (e.g., a conformal layer) means that the thicknessof the layer is substantially the same on all surfaces, or that thethickness variation is less than 15% of the nominal thickness of thelayer.

As previously noted herein, for the sake of brevity, conventionaltechniques related to semiconductor device and integrated circuit (IC)fabrication may or may not be described in detail herein. By way ofbackground, however, a more general description of the semiconductordevice fabrication processes that can be utilized in implementing one ormore embodiments of the present invention will now be provided. Althoughspecific fabrication operations used in implementing one or moreembodiments of the present invention can be individually known, thedescribed combination of operations and/or resulting structures of thepresent invention are unique. Thus, the unique combination of theoperations described in connection with the fabrication of asemiconductor device according to the present invention utilize avariety of individually known physical and chemical processes performedon a semiconductor (e.g., silicon) substrate, some of which aredescribed in the immediately following paragraphs.

In general, the various processes used to form a micro-chip that will bepackaged into an IC fall into four general categories, namely, filmdeposition, removal/etching, semiconductor doping andpatterning/lithography. Deposition is any process that grows, coats, orotherwise transfers a material onto the wafer. Available technologiesinclude physical vapor deposition (PVD), chemical vapor deposition(CVD), electrochemical deposition (ECD), molecular beam epitaxy (MBE)and more recently, atomic layer deposition (ALD) among others.Removal/etching is any process that removes material from the wafer.Examples include etch processes (either wet or dry), chemical-mechanicalplanarization (CMP), and the like. Reactive ion etching (RIE), forexample, is a type of dry etching that uses chemically reactive plasmato remove a material, such as a masked pattern of semiconductormaterial, by exposing the material to a bombardment of ions thatdislodge portions of the material from the exposed surface. The plasmais typically generated under low pressure (vacuum) by an electromagneticfield. Semiconductor doping is the modification of electrical propertiesby doping, for example, transistor sources and drains, generally bydiffusion and/or by ion implantation. These doping processes arefollowed by furnace annealing or by rapid thermal annealing (RTA).Annealing serves to activate the implanted dopants. Films of bothconductors (e.g., poly-silicon, aluminum, copper, etc.) and insulators(e.g., various forms of silicon dioxide, silicon nitride, etc.) are usedto connect and isolate transistors and their components. Selectivedoping of various regions of the semiconductor substrate allows theconductivity of the substrate to be changed with the application ofvoltage. By creating structures of these various components, millions oftransistors can be built and wired together to form the complexcircuitry of a modern microelectronic device. Semiconductor lithographyis the formation of three-dimensional relief images or patterns on thesemiconductor substrate for subsequent transfer of the pattern to thesubstrate. In semiconductor lithography, the patterns are formed by alight sensitive polymer called a photo-resist. To build the complexstructures that make up a transistor and the many wires that connect themillions of transistors of a circuit, lithography and etch patterntransfer steps are repeated multiple times. Each pattern being printedon the wafer is aligned to the previously formed patterns and slowly theconductors, insulators and selectively doped regions are built up toform the final device.

The flowchart and block diagrams in the Figures illustrate possibleimplementations of fabrication and/or operation methods according tovarious embodiments of the present invention. Variousfunctions/operations of the method are represented in the flow diagramby blocks. In some alternative implementations, the functions noted inthe blocks can occur out of the order noted in the Figures. For example,two blocks shown in succession can, in fact, be executed substantiallyconcurrently, or the blocks can sometimes be executed in the reverseorder, depending upon the functionality involved.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdescribed herein.

What is claimed is:
 1. A method of fabricating a magnetic stackarrangement of a laminated magnetic inductor, the method comprising:forming a first magnetic stack comprising one or more magnetic layersalternating with one or more insulating layers in a first inner regionof the laminated magnetic inductor; forming a second magnetic stackcomprising one or more magnetic layers alternating with one or moreinsulating layers opposite a surface of the first magnetic stack in anouter region of the laminated magnetic inductor; and forming a thirdmagnetic stack comprising one or more magnetic layers alternating withone or more insulating layers opposite a surface of the second magneticstack in a second inner region of the laminated magnetic inductor;wherein a thickness of an insulating layer in the second magnetic stackis greater than a thickness of an insulating layer in the first magneticstack.
 2. The method of claim 1 further comprising forming a firstdielectric layer opposite a surface of the first magnetic stack.
 3. Themethod of claim 2 further comprising forming a second dielectric layeropposite a surface of the third magnetic stack.
 4. The method of claim 3further comprising forming a conductive coil helically wrapping throughthe first and second dielectric layers.
 5. The method of claim 4,wherein the first and third magnetic stacks are positioned proximate tothe conductive coil.
 6. The method of claim 5, wherein the secondmagnetic stack is positioned between the first and third magnetic stackssuch that the second magnetic stack is further from the conductive coilthan either the first magnetic stack or the second magnetic stack. 7.The method of claim 1, wherein the one or more magnetic layers in thefirst magnetic stack comprise cobalt (Co), FeTaN, FeNi, FeAlO, or acombination thereof.
 8. The method of claim 1, wherein the one or moremagnetic layers in the first magnetic stack comprises a thickness ofabout 50 nm to about 500 nm.
 9. The method of claim 1, wherein the oneor more insulating layers in the first magnetic stack comprise alumina(Al₂O₃), silicon dioxide (SiO₂), a silicon nitride, a silicon oxynitride(SiO_(x)N_(y)), magnesium oxide (MgO), or a combination thereof.
 10. Themethod of claim 1, wherein the one or more insulating layers in thefirst magnetic stack comprises a thickness of about 0.5 nm to about 20nm.
 11. The method of claim 10, wherein the one or more insulatinglayers in the first magnetic stack comprises a thickness of about 1 nmto about 5 nm.
 12. The method of claim 1, wherein the thickness of aninsulating layer in the second magnetic stack is at least ten timesgreater than a thickness of an insulating layer in the first magneticstack.
 13. The method of claim 1, wherein the thickness of an insulatinglayer in the second magnetic stack is at least twenty times greater thana thickness of an insulating layer in the first magnetic stack.
 14. Amethod of fabricating a magnetic stack arrangement of a laminatedmagnetic inductor, the method comprising: forming a first insulatinglayer proximate to a conductive coil of the laminated magnetic inductor;forming a second insulating layer proximate to the conductive coilopposite a surface of the first insulating layer; and forming a thirdinsulating layer between the first and second insulating layers suchthat the third insulating layer is further from the conductive coil thaneither the first insulating layer or the second insulating layer;wherein a thickness of the third insulating layer is greater than athickness of either the first or second insulating layers.
 15. Themethod of claim 14, wherein the first insulating layer comprises athickness of about 0.5 nm to about 20 nm.
 16. The method of claim 14,wherein a thickness of the third insulating layer is at least twentytimes greater than a thickness of either the first or second insulatinglayers.
 17. A laminated magnetic inductor comprising: a first innerregion comprising one or more magnetic layers alternating with one ormore insulating layers; an outer region comprising one or more magneticlayers alternating with one or more insulating layers, the outer regionformed opposite a surface of the first inner region; and a second innerregion comprising one or more magnetic layers alternating with one ormore insulating layers, the second inner region formed opposite asurface of the outer region; wherein a thickness of an insulating layerin the outer region is greater than a thickness of an insulating layerin either the first or second inner regions.
 18. The laminated magneticinductor of claim 17, further comprising: a substrate; a firstdielectric layer positioned between the substrate and the first innerregion; a second dielectric layer formed opposite a surface of thesecond inner region; and a conductive coil helically wrapping throughportions of the first and second dielectric layers.
 19. The laminatedmagnetic inductor of claim 17, wherein the one or more insulating layersin the first inner region each comprise a thickness of about 0.5 nm toabout 20 nm.
 20. The laminated magnetic inductor of claim 19, wherein athickness of an insulating layer in the outer region is at least tentimes greater than a thickness of an insulating layer in either of thefirst or second inner regions.